Re: i386: allow platforms to override HAL_MEM_REAL_REGION_TOP

[Andrew Lunn <andrew at lunn dot ch>]

> It's been a while since we did this. I believe it is because the pcmb
> package already provides it and our platforms are based on pcmb in the
> same way that the pc platform is. Some of them differ in this detail
> since they don't have a BIOS. This patch allows the platform to override
> the pcmb provided default.
> 
> Perhaps the correct solution is to move hal_i386_mem_real_region_top
> from pcmb to the pc package? Or a weak symbol in pcmb (not too sure how
> those work though).

OK. Time to ask some stupid questions.....

What is the difference between the PC package and the PCMB package?
The description properties are:

CYGPKG_HAL_I386_PCMB
            The i386 PC Motherboard HAL package provides the
            support needed to run eCos binaries on a standard i386
            PC motherboard. This is a support package for various
            actual platform specific targets."

CYGPKG_HAL_I386_PC
            The i386 PC Target HAL package provides the
            support needed to run eCos binaries on a standard i386
            PC."

Its not clear to me what the differences is!

2nd question. Is the BIOS a property of the PCMB or of the PC? 

        Thanks
                Andrew